This application seeks support for analyses of data from a study of variations in practice patterns and outcomes in the treatment of six medical and surgical conditions at six hospitals in Massachusetts and California. This study will assess (a) the relationship between patient age and perception of health, controlling for disease severity, (b) the extent to which the process of care is related to patient age, after controlling for other medical variables, (c) the association between age and a wide range of outcomes, such as in-hospital complications, and physical, social, and mental functioning, and (d) variations in costs of care across different age groups. Data on case-mix, process of care, and outcomes will be collected on approximately 3,400 patients, of whom approximately 1,000 are expected to be greater than 65 years old. For each patient, data on sociodemographic characteristics, severity of illness, comorbidity, and certain process variables will be abstracted from the medical record. In addition, extensive data on resource use for each study patient will be compiled from each hospital's billing system. Outcome data will be collected using patient questionnaires and telephone interviews. Follow-up myocardial infarction, cholecystectomy, and transurethral prostatectomy at three months post-discharge. CABG patients will receive follow-up questionnaires six months post-discharge, and total hip replacement patients will be assessed one year after they are discharged.